Azimuthal correlations from transverse momentum conservation and possible local parity violation

TL;DR

This paper analytically examines how transverse momentum conservation influences azimuthal correlations in heavy ion collisions, highlighting that these effects can mimic signals of local parity violation and align with some experimental observations.

Contribution

The study provides an analytical calculation of momentum conservation effects on azimuthal correlations, clarifying their role as potential background signals in local parity violation searches.

Findings

Corrections are of the order of 1/N, matching observed signals.

Contributions have the same sign for like-sign and opposite-sign pairs.

Momentum dependence aligns qualitatively with STAR measurements.

Abstract

We analytically calculate the contribution of transverse momentum conservation to the azimuthal correlations that have been proposed as signals for possible local strong parity violation and recently measured in heavy ion collisions. These corrections are of the order of the inverse of the total final state particle multiplicity and thus are of the same order as the observed signal. The corrections contribute with the same sign to both like-sign and opposite-sign pair correlations. Their dependence on the momentum is in qualitative agreement with the measurements by the STAR collaboration, while the pseudorapidity dependence differs from the data.